A conventional connector 11 includes a clamp-type socket as a connecting member with a flat cable 12, as shown in FIG. 1. The clamp-type socket 101 includes two rows of elastic metal strips 102 arranged on inner surfaces thereof in a manner corresponding to a plurality of pins 103 of the flat cable 12, respectively, so as to permit mechanical and electric connection between the elastic metal strips 102 and the pins 103 after the flat cable 12 is inserted into the connector 11. Thereby, the connector can transmit a signal from an element connected therewith to another element connected with the flat cable. For example, the connector 11 can obtain power from a power supply 13 through wires (not shown), and transmit the power to a circuit board 14 through the combination of the metal strips 102 and the pins 103.
It is apparent, however, that in the conventional connector 11, the metal strips 102 clamp and secure the pins 103 therein only by elastic force of themselves. Consequently, the mechanical connection between the elastic metal strips 102 and the pins 103 is likely to be released owing to the weakening of the elastic force of the metal strips 102 so as to result in poor electric connection between the power supply 13 and the circuit board 14. The elastic force can be weakened for many reasons, such as natural decay or frequent plugged and unplugged operations.
Another kind of signal transmission is conducted by conductive layers as shown in FIG. 2 rather than the metal strips and wires as mentioned above. In FIG. 2, two conductive pieces 201 and 202 having therebetween an insulating layer 203 are connected to a power supply (not shown) by one end and to a connector 21 by another end. The two conductive pieces 201 and 202 are connected to two plates 211 and 212 of the connector 21, respectively, and the relative position of the two plates 211 and 212 are flexibly adjusted by a spring element 213. When a flat cable 22 of a circuit board 24 is inserted into the connector 21 from the entrance between the two plates 211 and 212 by a bare metal end 221 thereof, the spring element 213 props open the entrance to allow the flat cable 22 to enter the connector 21, and the flat cable 22 is able to be clamped between the two conductive pieces 201 and 202 by the elastic force of the spring element 213. Accordingly, power can be transmitted from the power supply to the circuit board. Such power transmission means has an advantage of eliminating the induction effect of wires. In other words, power can be transmitted in a condition of almost no induction so that a voltage drop (.DELTA.V=L(di/dt)) resulting from an instantaneous high current owing to a power-on or wake-up operation will not occur, and thus the quality of power supplying can be maintained. Such means is especially preferably applied to an electronic circuit of low voltage, e.g. a microprocessor of 3.3 volts or less.
The power transmission means as mentioned above, however, maintains the clamp relationship between the conductive pieces and the flat cable only by elastic force of the spring element. Therefore, the close contact between the conductive pieces and the flat cable is subject to change with the weakening of the elastic force of the spring element. Also, the elastic force can be weakened for many reasons, such as natural decay or frequent plugged and unplugged operations.